目录
目录
前言
核心流程函数调用路径
GetReplicationAnalysis
故障类型和对应的处理函数
拓扑结构警告类型
与MHA相比
前言
Orchestrator另外一个重要的功能是监控集群,发现故障。根据从复制拓扑本身获得的信息,它可以识别各种故障场景。Orchestrator介绍四-失败/故障检测_orchestrator 心跳-CSDN博客
核心流程函数调用路径
ContinuousDiscovery
--> CheckAndRecover // 检查恢复的入口函数
--> GetReplicationAnalysis // 查询SQL,根据实例的状态确定故障或者警告类型。检查复制问题 (dead master; unreachable master; 等)
--> executeCheckAndRecoverFunction // 根据分析结果选择正确的检查和恢复函数。然后会同步执行该函数。
--> getCheckAndRecoverFunction // 根据分析结果选择正确的检查和恢复函数。然后会同步执行该函数。
--> runEmergentOperations //
--> checkAndExecuteFailureDetectionProcesses // 尝试往数据库中插入这个故障发现记录,然后执行故障发现阶段所需的操作,执行 OnFailureDetectionProcesses (故障发现阶段的)钩子脚本
--> AttemptFailureDetectionRegistration // 尝试往数据库中插入故障发现记录 ,如果失败 意味着这个问题可能已经被发现了,
--> checkAndRecoverDeadMaster // 根据故障情况 执行恢复,这里选择DeadMaster 故障类型举例
--> AttemptRecoveryRegistration // 尝试往数据库中插入一条恢复记录;如果这一尝试失败,那么意味着恢复已经在进行中。
--> recoverDeadMaster // 用于恢复DeadMaster故障类型的函数,其中包含了完整的逻辑。会执行PreFailoverProcesses 钩子脚本
GetReplicationAnalysis
该函数将检查复制问题 (dead master; unreachable master; 等),根据实例的状态确定故障或者警告类型。
该函数会运行一个复杂SQL ,该SQL会每秒执行一次 ,执行间隔是由定时器 recoveryTick决定 ,SQL如下
SELECTmaster_instance.hostname,master_instance.port,master_instance.read_only AS read_only,MIN(master_instance.data_center) AS data_center,MIN(master_instance.region) AS region,MIN(master_instance.physical_environment) AS physical_environment,MIN(master_instance.master_host) AS master_host,MIN(master_instance.master_port) AS master_port,MIN(master_instance.cluster_name) AS cluster_name,MIN(master_instance.binary_log_file) AS binary_log_file,MIN(master_instance.binary_log_pos) AS binary_log_pos,MIN(IFNULL(master_instance.binary_log_file = database_instance_stale_binlog_coordinates.binary_log_fileAND master_instance.binary_log_pos = database_instance_stale_binlog_coordinates.binary_log_posAND database_instance_stale_binlog_coordinates.first_seen < NOW() - interval 10 second,0)) AS is_stale_binlog_coordinates,MIN(IFNULL(cluster_alias.alias,master_instance.cluster_name)) AS cluster_alias,MIN(IFNULL(cluster_domain_name.domain_name,master_instance.cluster_name)) AS cluster_domain,MIN(master_instance.last_checked <= master_instance.last_seenand master_instance.last_attempted_check <= master_instance.last_seen + interval 6 second) = 1 AS is_last_check_valid,/* To be considered a master, traditional async replication must not be present/valid AND the host should either *//* not be a replication group member OR be the primary of the replication group */MIN(master_instance.last_check_partial_success) as last_check_partial_success,MIN((master_instance.master_host IN ('', '_')OR master_instance.master_port = 0OR substr(master_instance.master_host, 1, 2) = '//')AND (master_instance.replication_group_name = ''OR master_instance.replication_group_member_role = 'PRIMARY')) AS is_master,MIN(master_instance.replication_group_name != ''AND master_instance.replication_group_member_state != 'OFFLINE') AS is_replication_group_member,MIN(master_instance.is_co_master) AS is_co_master,MIN(CONCAT(master_instance.hostname,':',master_instance.port) = master_instance.cluster_name) AS is_cluster_master,MIN(master_instance.gtid_mode) AS gtid_mode,COUNT(replica_instance.server_id) AS count_replicas,IFNULL(SUM(replica_instance.last_checked <= replica_instance.last_seen),0) AS count_valid_replicas,IFNULL(SUM(replica_instance.last_checked <= replica_instance.last_seenAND replica_instance.slave_io_running != 0AND replica_instance.slave_sql_running != 0),0) AS count_valid_replicating_replicas,IFNULL(SUM(replica_instance.last_checked <= replica_instance.last_seenAND replica_instance.slave_io_running = 0AND replica_instance.last_io_error like '%error %connecting to master%'AND replica_instance.slave_sql_running = 1),0) AS count_replicas_failing_to_connect_to_master,MIN(master_instance.replication_depth) AS replication_depth,GROUP_CONCAT(concat(replica_instance.Hostname,':',replica_instance.Port)) as slave_hosts,MIN(master_instance.slave_sql_running = 1AND master_instance.slave_io_running = 0AND master_instance.last_io_error like '%error %connecting to master%') AS is_failing_to_connect_to_master,MIN(master_downtime.downtime_active is not nulland ifnull(master_downtime.end_timestamp, now()) > now()) AS is_downtimed,MIN(IFNULL(master_downtime.end_timestamp, '')) AS downtime_end_timestamp,MIN(IFNULL(unix_timestamp() - unix_timestamp(master_downtime.end_timestamp),0)) AS downtime_remaining_seconds,MIN(master_instance.binlog_server) AS is_binlog_server,MIN(master_instance.pseudo_gtid) AS is_pseudo_gtid,MIN(master_instance.supports_oracle_gtid) AS supports_oracle_gtid,MIN(master_instance.semi_sync_master_enabled) AS semi_sync_master_enabled,MIN(master_instance.semi_sync_master_wait_for_slave_count) AS semi_sync_master_wait_for_slave_count,MIN(master_instance.semi_sync_master_clients) AS semi_sync_master_clients,MIN(master_instance.semi_sync_master_status) AS semi_sync_master_status,SUM(replica_instance.is_co_master) AS count_co_master_replicas,SUM(replica_instance.oracle_gtid) AS count_oracle_gtid_replicas,IFNULL(SUM(replica_instance.last_checked <= replica_instance.last_seenAND replica_instance.oracle_gtid != 0),0) AS count_valid_oracle_gtid_replicas,SUM(replica_instance.binlog_server) AS count_binlog_server_replicas,IFNULL(SUM(replica_instance.last_checked <= replica_instance.last_seenAND replica_instance.binlog_server != 0),0) AS count_valid_binlog_server_replicas,SUM(replica_instance.semi_sync_replica_enabled) AS count_semi_sync_replicas,IFNULL(SUM(replica_instance.last_checked <= replica_instance.last_seenAND replica_instance.semi_sync_replica_enabled != 0),0) AS count_valid_semi_sync_replicas,MIN(master_instance.mariadb_gtid) AS is_mariadb_gtid,SUM(replica_instance.mariadb_gtid) AS count_mariadb_gtid_replicas,IFNULL(SUM(replica_instance.last_checked <= replica_instance.last_seenAND replica_instance.mariadb_gtid != 0),0) AS count_valid_mariadb_gtid_replicas,IFNULL(SUM(replica_instance.log_binAND replica_instance.log_slave_updates),0) AS count_logging_replicas,IFNULL(SUM(replica_instance.log_binAND replica_instance.log_slave_updatesAND replica_instance.binlog_format = 'STATEMENT'),0) AS count_statement_based_logging_replicas,IFNULL(SUM(replica_instance.log_binAND replica_instance.log_slave_updatesAND replica_instance.binlog_format = 'MIXED'),0) AS count_mixed_based_logging_replicas,IFNULL(SUM(replica_instance.log_binAND replica_instance.log_slave_updatesAND replica_instance.binlog_format = 'ROW'),0) AS count_row_based_logging_replicas,IFNULL(SUM(replica_instance.sql_delay > 0),0) AS count_delayed_replicas,IFNULL(SUM(replica_instance.slave_lag_seconds > 10),0) AS count_lagging_replicas,IFNULL(MIN(replica_instance.gtid_mode), '') AS min_replica_gtid_mode,IFNULL(MAX(replica_instance.gtid_mode), '') AS max_replica_gtid_mode,IFNULL(MAX(case when replica_downtime.downtime_active is not nulland ifnull(replica_downtime.end_timestamp, now()) > now() then '' else replica_instance.gtid_errant end),'') AS max_replica_gtid_errant,IFNULL(SUM(replica_downtime.downtime_active is not nulland ifnull(replica_downtime.end_timestamp, now()) > now()),0) AS count_downtimed_replicas,COUNT(DISTINCT case when replica_instance.log_binAND replica_instance.log_slave_updates then replica_instance.major_version else NULL end) AS count_distinct_logging_major_versionsFROMdatabase_instance master_instanceLEFT JOIN hostname_resolve ON (master_instance.hostname = hostname_resolve.hostname)LEFT JOIN database_instance replica_instance ON (COALESCE(hostname_resolve.resolved_hostname,master_instance.hostname) = replica_instance.master_hostAND master_instance.port = replica_instance.master_port)LEFT JOIN database_instance_maintenance ON (master_instance.hostname = database_instance_maintenance.hostnameAND master_instance.port = database_instance_maintenance.portAND database_instance_maintenance.maintenance_active = 1)LEFT JOIN database_instance_stale_binlog_coordinates ON (master_instance.hostname = database_instance_stale_binlog_coordinates.hostnameAND master_instance.port = database_instance_stale_binlog_coordinates.port)LEFT JOIN database_instance_downtime as master_downtime ON (master_instance.hostname = master_downtime.hostnameAND master_instance.port = master_downtime.portAND master_downtime.downtime_active = 1)LEFT JOIN database_instance_downtime as replica_downtime ON (replica_instance.hostname = replica_downtime.hostnameAND replica_instance.port = replica_downtime.portAND replica_downtime.downtime_active = 1)LEFT JOIN cluster_alias ON (cluster_alias.cluster_name = master_instance.cluster_name)LEFT JOIN cluster_domain_name ON (cluster_domain_name.cluster_name = master_instance.cluster_name)WHEREdatabase_instance_maintenance.database_instance_maintenance_id IS NULLAND '' IN ('', master_instance.cluster_name)GROUP BYmaster_instance.hostname,master_instance.portHAVING(MIN(master_instance.last_checked <= master_instance.last_seenand master_instance.last_attempted_check <= master_instance.last_seen + interval 6 second) = 1/* AS is_last_check_valid */) = 0OR (IFNULL(SUM(replica_instance.last_checked <= replica_instance.last_seenAND replica_instance.slave_io_running = 0AND replica_instance.last_io_error like '%error %connecting to master%'AND replica_instance.slave_sql_running = 1),0)/* AS count_replicas_failing_to_connect_to_master */> 0)OR (IFNULL(SUM(replica_instance.last_checked <= replica_instance.last_seen),0)/* AS count_valid_replicas */< COUNT(replica_instance.server_id)/* AS count_replicas */)OR (IFNULL(SUM(replica_instance.last_checked <= replica_instance.last_seenAND replica_instance.slave_io_running != 0AND replica_instance.slave_sql_running != 0),0)/* AS count_valid_replicating_replicas */< COUNT(replica_instance.server_id)/* AS count_replicas */)OR (MIN(master_instance.slave_sql_running = 1AND master_instance.slave_io_running = 0AND master_instance.last_io_error like '%error %connecting to master%')/* AS is_failing_to_connect_to_master */)OR (COUNT(replica_instance.server_id)/* AS count_replicas */> 0)ORDER BYis_master DESC,is_cluster_master DESC,count_replicas DESC\G
故障类型和对应的处理函数
故障类型 | 处理函数 |
NoProblem | 没有 |
DeadMasterWithoutReplicas | 没有 |
DeadMaster | checkAndRecoverDeadMaster |
DeadMasterAndReplicas | checkAndRecoverGenericProblem |
DeadMasterAndSomeReplicas | checkAndRecoverDeadMaster |
UnreachableMasterWithLaggingReplicas | checkAndRecoverGenericProblem |
UnreachableMaster | checkAndRecoverGenericProblem |
MasterSingleReplicaNotReplicating | |
MasterSingleReplicaDead | |
AllMasterReplicasNotReplicating | checkAndRecoverGenericProblem |
AllMasterReplicasNotReplicatingOrDead | checkAndRecoverGenericProblem |
LockedSemiSyncMasterHypothesis | |
LockedSemiSyncMaster | checkAndRecoverLockedSemiSyncMaster |
MasterWithTooManySemiSyncReplicas | checkAndRecoverMasterWithTooManySemiSyncReplicas |
MasterWithoutReplicas | |
DeadCoMaster | checkAndRecoverDeadCoMaster |
DeadCoMasterAndSomeReplicas | checkAndRecoverDeadCoMaster |
UnreachableCoMaster | |
AllCoMasterReplicasNotReplicating | |
DeadIntermediateMaster | checkAndRecoverDeadIntermediateMaster |
DeadIntermediateMasterWithSingleReplica | checkAndRecoverDeadIntermediateMaster |
DeadIntermediateMasterWithSingleReplicaFailingToConnect | checkAndRecoverDeadIntermediateMaster |
DeadIntermediateMasterAndSomeReplicas | checkAndRecoverDeadIntermediateMaster |
DeadIntermediateMasterAndReplicas | checkAndRecoverGenericProblem |
UnreachableIntermediateMasterWithLaggingReplicas | checkAndRecoverGenericProblem |
UnreachableIntermediateMaster | |
AllIntermediateMasterReplicasFailingToConnectOrDead | checkAndRecoverDeadIntermediateMaster |
AllIntermediateMasterReplicasNotReplicating | |
FirstTierReplicaFailingToConnectToMaster | |
BinlogServerFailingToConnectToMaster | |
// Group replication problems | |
DeadReplicationGroupMemberWithReplicas | checkAndRecoverDeadGroupMemberWithReplicas |
拓扑结构警告类型
- StatementAndMixedLoggingReplicasStructureWarning
- StatementAndRowLoggingReplicasStructureWarning
- MixedAndRowLoggingReplicasStructureWarning
- MultipleMajorVersionsLoggingReplicasStructureWarning
- NoLoggingReplicasStructureWarning
- DifferentGTIDModesStructureWarning
- ErrantGTIDStructureWarning
- NoFailoverSupportStructureWarning
- NoWriteableMasterStructureWarning
- NotEnoughValidSemiSyncReplicasStructureWarning
与MHA相比
MHA探活
核心功能主要有 MHA::HealthCheck::wait_until_unreachable 实现:
-
该函数通过一个死循环,检测 4 次,每次 sleep ping_interval 秒(这个值在配置文件指定,参数是 ping_interval),持续四次失败,就认为数据已经宕机;
-
如果有二路检测脚本,需要二路检测脚本检测主库宕机,才是真正的宕机,否则只是推出死循环,结束检测,不切换
-
通过添加锁来保护数据库的访问,防止脚本多次启动;
-
该函数可调用三种检测方法:ping_select、ping_insert、ping_connect
MHA探活流程图
MHA | OC | |
故障类型 | 故障类型单一, 主要就是主库是否存活 | 故障类型丰富 有多种故障与警告类型 见上面的总结 |
探活节点 | 支持多个节点探活 即manager服务器与二次检查脚本中定义的服务器 | 多个OC节点 以及 配合该实例的从库复制状态是否正常进行检测 |
探活方式 | ping_select、 ping_insert、 ping_connect | 查询被管理的数据库,将数据写入到OC的后台管理数据库中,进行时间戳的比较或状态值比较等方式 |
探活间隔 | 默认3秒 | 默认每1秒 |
探活次数 | 4次 | 1次 |
故障探测速度 | 慢,需要多次探活。 | 快 |
探活理念 | 多次多个节点避免网络抖动等 | 配合从副本的主从状态以及OC节点的探活 |